|
(11) | EP 0 147 643 B1 |
| (12) | EUROPEAN PATENT SPECIFICATION |
|
|
| (54) |
Electroerosion printing Elektroerosionsdruck Impression par électroérosion |
|
|
|||||||||||||||||||||||||||||||
| Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention). |
[0001] The invention relates to electroerosion printing and to recording materials for use as human readable material and for use in the production of direct negatives and direct offset masters.
[0002] Electroerosion printing is a well-known technique for producing markings, such as letters, numbers, symbols, patterns, such as circuit patterns, or other legible or coded indicia on recording material in response to an electric signal which removes or erodes material from the surface of the recording material as the result of spark initiation (arcing).
[0003] The surface which is electrically eroded or removed to provide such indicia on the recording material is usually a thin film of conductive material which is vaporized in response to localized heating associated with sparking (arcing) initiated by applying an electric current to an electrode in contact with the surface of a recording material comprising the thin conductive film on a non-conductive backing or support. In the present state of the technology, the thin conductive film is usually a thin film of vaporizable metal, such as aluminum. In practice, a multi-styli print head is scanned across the aluminum surface of the recording medium and electrodes are selectively energized to form images in accordance with digitally coded image information. Electroerosion materials and processes are useful to produce directly, human readable images, photomasks, etc, for a number of such applications, flexible substrates of paper and plastic have been employed with thickness on the order of 51 to 130 pm (2 to 5 mil) with vapor deposited aluminum films of a thickness on the order of 0.5 to 5 micrometers having been utilized. For details on materials heretofore used in electroerosion printing, see U.S. Patent 4,082,902, Suzuki, and U.S. Patent 4,086,853, Figov.
[0004] In high resolution and high speed electroerosion printing, the print head used to record the desired information may be comprised of thirty or more styli which move in relation to the surface of specially prepared recording media. Electrical writing signals are fed to the stylus or styli to provide controlled electrical pulses which generate arcing at the surface of the recording material selectively to heat and remove by evaporation a layer, usually aluminum, of the recording material; the removed material corresponds to the indicia which are to be recorded.
[0005] A common problem with high resolution electroerosion printing processes using conventional metallized plastic substrates is that severe scratching of the aluminum layer occurs during writing. This may be attributable to relatively low resistance of a thin aluminum film to mechanical abrasion or to other causes, including plastic deformation of the substrate. The thin conductive film, for example, the vapor-deposited thin aluminum film, apparently cannot withstand the high strains generated when the support or substrate is deformed, resulting in scratching. Also, in the instance that the styli cold-weld to the thin aluminum conductive layer, the structure may suffer shear, either at the aluminum-substrate interface or below it in the substrate itself.
[0006] Various measures have been proposed to combat the problem of scratching. For example, it has been suggested to suppress the plastic deformation of the substrate by creating a thin hard layer below the aluminum. The hardness of the layer would be selected to prevent the undesired deformation, but the thickness of the layer would be such that the gross flexibility of the sheet necessary for electroerosion writing and handling would be maintained. The method of obtaining this hard layer involves the incorporation of small hard particles, such as silica, in a suitable polymeric binder.
[0007] This system as described in EP-A-112,005 was found in fact to decrease scratching caused by the polymersubstrate deformation mechanism. Although such a base layer between the plastic substrate and the aluminum film provides substantial improvement in scratch resistance, some scratching still remains, caused by the fact that the hard particles in these coatings are easily abraded during the printing process due to high local pressure caused by the styli on such rough surfaces.
[0008] In EP-A-113007 there is disclosed electroerosion recording materials comprising a nonconductive support, a thin layer or conductive materials capable of being removed by evaporation during electroerosion recording and an improved intermediate layer of thin, hard cross-linked polymer between said support and said layer of conductive material. The cross-linked polymer layer, such as a thermoset cellulose-acetate-butyrate polymer (CAB) cross-linked with polyisocyanate, and containing hard particles such as silica, is found to reduce plastic deformation of the support in response to stylus writing pressure and thus minimizes scratching during the electroerosion process, while the surface roughness is sufficient to scour off from the stylus debris formed during electroerosion recording.
[0009] However, with the employment of either a non- cross-linked polymer based or the above- described cross-linked polymer based intermediate layer, it has been necessary to include a lubricant overcoat to further improve the scratch- resistance and prior quality of the electroerosion material, lubricant coatings containing conductive particles of high lubricity, such as graphite, in a polymeric binder are disclosed in EP-A-113007.
[0010] Although with the application of a lubricant overlayer and a relatively hard cross-linked base layer, it has been possible to obtain much better scratch resistance, further modifications of the chemistry of various coatings are desired for an overall improvement so as to obtain reduced head wear, and reduced "fouling" or "baking" problem which is caused by the accumulation of eroded debris on the print head during the writing process.
[0011] U.S. Patent 3,740,254, Lansbury et al, describes an isocyanate-ended polyurethane composition, i.e. a prepolymer, as a primer for the deposition of thin aluminum films on various substrates including plastic substrates. The purpose here is to improve adhesion of the aluminum film.
[0012] U.S. Patent 4,339,758 of Bhatia et al, describes an electrosensitive recording that uses a silicon dioxide containing resinous base layer between support and the overlying metallic film.
[0013] In accordance with the present invention, it has been found that electroerosion recording materials having superior resistance to surface abrasion or scratching of the thin conductive film, such as aluminum, improved adhesion of aluminum to the base layer, marked reduction in the print head wear, reduced "fouling" and "baking" and an overall improvement in print quality can be produced by providing between the conductive film and the support a thin layer comprising graphite fluoride and/or fluorocarbon polymers such as the TeflonR resins as solid lubricants and a hard particulate material such as silica, in a polymer binder, said layer having sufficient hardness to substantially eliminate scratching due to plastic deformation of the support without reducing the handling and writing qualities of the recording material. The recording material of this invention has a further advantage of process simplification since it does not require a lubricant overcoat and thus, eliminates the extra step of applying a lubricating overcoat that is needed in prior techniques as discussed hereinabove.
[0014] In one version of the present invention, the electroerosion recording material has a light transmissive intermediate layer comprising graphite fluoride and/or fluorocarbon resin as lubricants and white hard particulate material in a polymeric binder, thereby enabling the recording material to be used in preparing direct negatives and/or offset printing masters.
[0015] In another embodiment of the invention, the intermediate layer contains graphite fluoride and/ or fluorocarbon resins such as 'Teflon' along with other solid lubricants such as graphite, and a hard particulate material such as silica in a polymeric binder. The incorporation of graphite fluoride and/or fluorocarbon resins in coating formulations for the intermediate layer has been found to markedly increase the adhesion of a conductive metal such as aluminum to the intermediate layer.
[0016] The invention will now be further described with reference to the accompanying drawings, in which:
Figure 1 of the drawings is a general schematic rendering of an illustrative electroerosion printing system.
Figure 2 of the drawings is a cross-sectional view of a direct negative made in accordance with this invention.
Figure 3 of the drawings is a cross-sectional view of an offset master made in accordance with this invention.
The present invention is concerned with improvements in electroerosion recording materials and in particular such materials useful in the production of direct negative and offset printing masters.
[0017] In the broadest sense, the invention comprises the provision between the thin conductive film and the plastic support member, such as a polyester, e.g. MylarR, of a hard, lubricating, thermoset polymeric film or layer which reduces plastic deformation of the support member during electroerosion writing sufficiently so that abrasion of the thin conductive film, usually evaporated aluminum, is minimized. The hardness, thickness and asperities caused by inorganic fillers such as silica, of this intermediate layer are also selected so that the handling and writing characteristics of the recording material are not adversely affected. With the inclusion of graphite fluorite and/or fluorocarbon resins such as TeflonR as a solid lubricant, there is improved adhesion of aluminum to the base layer and sufficient scratch resistance without the need for a lubricating overcoat. A lubricant overcoat is generally required where the intermediate layer does not contain graphite fluoride and/or fluorocarbon resins individually or in combination with other lubricants.
[0018] According to this invention, a superior hard, thin underlayer for a conductive metal layer is provided for electroerosion recording materials by inclusion of graphite fluoride and/or TeflonR resin as micropowder available from du Pont and a hard particulate material, preferably in a thermoset cross-linked polymer binder, as the underlayer.
[0019] Graphite fluorides such as the FluorographiteTM product of Ozark-Mahoning can be obtained in particle size of the order of 3-40 pm and can be employed either as a single solid lubricant component in the base layer coating composition or in combination with fluorocarbon resins and/or with essentially any laminar solid of high lubricity. Among the co-lubricant solids with graphite- fluoride and/or fluorocarbon resins, the preferred material is graphite although other lamellar or conductive lubricant materials which are expected to be useful include, for example, MoS2, WS2, Agl, Sn, Cu, Ag, Pb, Bi, AI, Zn, etc. Non- conductive particulate lubricants that may be used in combination with TeflonR resins and/or graphite fluoride include boron nitride and boric acid.
[0020] The hard particles are preferably Si02, but could be other materials known in the art, such as, titanium dioxide, zinc oxide, alumina, calcium carbonate, boron nitride, etc., having a size of about 0.5 to 10.0 pm. The Si02 pigment of a particle size of from about 0.5 to 10 microns, preferably about 1 to 5 microns, is preferred and should be added to the binder in the range of from about 2 to 25% by weight, based on the cured film. The silica particles act as a filler in the system to prevent blocking and also help to improve wear-resistance of the coating.
[0021] The lubricating particles are selected to be physically and chemically compatible with the heretofore described hard particle-binder systems. Thus, the lubricating particles of graphite fluoride will range in size from about 1 to 20 microns, preferably about 2 to 5 microns, and the TeflonR micropowder resins are available from du Pont in particle size ranging from 0.5-5 microns.
[0022] When graphite fluoride is used as the sole or major lubricating particle, for example in the fabrication of the recording material, it can be used in an amount of about 0.5 to 5 weight percent, based on the cured film. On the other hand, when the graphite fluoride is employed in combination with other solid lubricants, a lesser amount of about 0.2 to 2 wt% can be conveniently employed, with the overall particulate lubricant content of the cured film being about 2 to 10% by weight. It is observed that graphite fluoride tends to phase separate such that it concentrates on the surface of the coating upon curing to cause spatial fixation of the graphite fluoride particles in the polymeric binder.
[0023] Graphite fluoride (CFx)n such as the fluorog- raphiteTM product of Ozark-Mahoning is available in a range of degrees of fluorination with coloration varying from black through grays to white with increasing fluorination. For example, FluorographiteTM having a degree of fluorination (x) of 0.25 is black, of 0.9 is light gray and about 1 is snow white. FluorographiteTM with x=0.4-0.5 can be used in providing a light transmissive base layer for use in direct negative and/or offset master applications. For example, in preparing a 5 um thick coating of urethane cross-linked CAB (cellulose-acetate-butyrate)-silica-FluorographiteTM (x=0.4-0.5) on a MylarR sheet with a pigment-volume concentration (PVC) of silica and FluorographiteTM of 10 and 2.5%, respectively, which has 83% light transmission.
[0024] On a PVC basis the hard particles are present in about 5 to 25%, and the lubricant particles in about 0.5 to 5%. Where graphite fluoride is being used parimarilyto aid in surface adhesion, its PVC in the intermediate layer can be about 0.2 to 1.5%, with the remainder of particulate lubricant PVC being provided by other conductive or non-conductive lubricant particles.
[0025] When a fluorocarbon resin is used as the sole or the major lubricant particulate. It an be used in an amount of about 0.5 to 5 weight percent based on the total solids in the cured coatings. However, when such a resin is employed as a co-lubricant with graphite fluoride or other solid lubricants, a lesser amount of about 0.2 to 2 weight percent generally is sufficient to provide an overall improvement in the performance of the recording material according to this invention. Among a variety of fluorocarbon resins available, the Tef-IonR resins available as micropowders in particle size of 0.5-5 micron from Du Pont, are the preferred materials to provide base layers having light transmissivity suitable for use in direct negative or direct offset-master applications.
[0026] The polymeric binder can be selected from the binders used in preparing hard cross-linked and non-crosslinked intermediate layers which can contain hard particles, as disclosed in the heretofore mentioned EP-A-113005.
[0027] Thus, the polymeric binder can be selected from cellulose esters and ethers such as cellulose acetate butyrate (CAB), ethyl cellulose, nitrocellulose and cellulose acetate, or other polymers including polyvinylbutyral, novolak resins, epoxys, styryl allyl alcohol, etc. where desired or necessary, thermal, radiation-induced or chemical curing and/or cross-linking can be carried out.
[0028] Preferably, the polymeric binder forms a highly cross-linked polymer coating, and the following are representative examples of various cross- linked polymer systems for application according to this invention:
[0029] (a) Urethane cross-linked cellulosic coatings formed from cellulose derivatives and aromatic or aliphatic polyisocyanates in the presence of suitable dispersing agents, catalysts and wetting agents well known in those skilled in the polyurethane art. Suitable cellulose derived materials are: Cellulose acetate butyrate (CAB), ethyl cellulose (EC), nitrocellulose, cellulose acetate and cellulose diacetate, etc. Alternate materials containing unsubstituted hydroxyl groups for reaction with polyisocyanates to form cross-linked polyurethanes are: polyvinylbutyral, Bakelite phenoxy resins, phenolic resins, epoxies sych as Eponols and polyether glycols such as "Teracol" (from du Pont), and poly(styrylallyl alcohol). Typical polyisocyanates that react with available -OH groups of cellulosic binders or alternate systems include toluene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate-based systems such as Desmodur H-75 (aliphatic prepolymer, Mobay Chemical Co.) and Mondur Resins such as CB-60 and CB-75, and Mondur HC. Melamine cross-linking agents can also be employed to obtain thermoset coatings with the above binders. Inorganic fillers such as Si02, alumina CaC03, Ti02 and calcium silicate, etc. of particle size ranging from 0.5 pm to 10 µm can be incorporated by the usual techniques of grinding or milling together with the binder, the urethane solvent such as MEK-Toluene mixture, and a suitable dispersing agent such as Multron R221-75, a saturated polyester resin by Mobay Chemicals.
[0030] The urethane forming reactions of the above- described binders and urethane prepolymers are catalyzed by organometallic reagents such as stannous oleate, stannous octoate, dibutyl-tin dioctoate, dibutyl-tin dilaurate, calcium or cobalt naphthenate and also tertiary amines. Further acceleration of the cross-linking reaction can be achieved by thermal treatment of the coatings.
[0031] (b) Cross-linked polymer coatings with beneficial properties can be obtained by the use of radiation curable acrylated polyurethane oligomers of the type "UVITHANE 783" and "UVITHANE 788" available from Thiokol Chemical Div. Inorganic fillers such as silica can be dispersed by conventional techniques prior to coating.
[0032] Highly cross-linked films can also be obtained by thermal or radiation-induced copolymeriza- tion/co-cross-linking of the above UV curable urethane oligomers with added multifunctional monomers such as pentaerythritol triacrylate (PETA) and trimethylol-propane triacrylate (TMPTA) available from Celanese Corporation.
[0033] (c) Desired cross-linked films can also be formed by thermal, microwave, or UV curing of coatings cast from blends of acrylated cellulosic derivatives and UV curable urethane oligomers described in (b) above.
[0034] While a number of materials and approaches described above are suitable for hard polymer films to achieve superior quality electroerosion printing materials, we have found that excellent anti-abrasion properties, and writing characteristics can be achieved by utilizing cellulose derived binders such as cellulose acetate butyrate or ethyl cellulose with polyisocyanates as cross-linking agents. The material may be used filled with silica particles plus the lubricant particles.
[0036] The support or substrate is selected from those materials heretofore used in preparing the type of electroerosion recording material desired, for example, MylarR polyester, paper or polyolefin such as polypropylene.
[0037] The conductive recording layer, such as AI, can be applied by vacuum evaporation or sputtering, as known in the art. Desired resistivity is in the area of 1 to 5 ohms/cm2.
[0038] In the preparation of offset masters, the intermediate layer is sufficiently hydrophobic to maintain good hydrophilic-hydrophobic mapping between the hydrophilic AI background and the hydrophobic written region due to exposed intermediate layer, when oleophilic inks are used in preparing copies from the offset master.
[0039] The detailed description of the invention can be better appreciated by reference to the accompanying drawings. Fig. 1 illustrates schematically an electroerosion printing system 1 which includes a source of electrical energy 2, which is connected with writing control means 3 for controlling the flow (voltage and pulse length) of electrical current to styli 4 which are electrodes which contact the surface of the electroerosion recording material 5.
[0040] In operation, electric current pulses corresponding to information to be printed on the recording material 5 are transmitted through the writing control systems 3 to the styli 4. As a result, electrical discharges are generated at the surface of the recording material 5, and the temperature of the thin surface film is locally raised, causing evaporation of the surface film or layer and exposing the underlying material to produce the desired image.
[0041] Means (not shown) are provided for moving the styli 4 relative to and in contact with the surface of the recording material 5. As the styli 4 move relative to the recording material 5 and the writing control means 3 direct pulses of current to the styli of sufficient voltage to cause arcing and evaporation of a conductive layer of the material, there can be recorded desired information, patterns and graphics of any kind.
[0042] Referring to Figs. 2 and 3, the electroerosion recording material of this invention 6 is shown in cross section to comprise a support 7 of paper, polymer film, etc., a thin, conductive, evaporable layer of film 8, and a tough, hard film 10 containing lubricant particles and hard particles positioned between the support 7 and the evaporable layer 8. This intermediate film 10 is comprised of fluorocarbon resins and/or graphite fluoride as solid lubricants along with small hard particles such as silica in a suitable polymeric binder, for example, urethane cross-linked cellulose-acetate-butyrate (CAB) as disclosed in EP-A-113005.
[0043] The intermediate layer serves to reduce scratching of the material during electroerosion printing to the extent that a lubricant top coat is not needed. The evaporable film 8 usually has a resistance from about 1 to 5 ohms per square centimeter and is frequently a vapor-deposited thin film of aluminum.
[0044] Where the backing or support is a light transparent or transmissive material and the intermediate layer is also transparent or light transmissive, the resulting product can be used as a photomask or direct-negative medium for the development of photosensitive materials, e.g., in the production of offset lithography masters, circuit boards, etc. Where the styli have been energized and the conductive film burned off light windows 11 are provided through the transparent backing so that the material is rendered selectively light (arrows) transmissive and may then be used in direct-photo-negative or like applications.
[0045] Where the material is to be used as an offset printing master as in Fig. 3, the intermediate layer 10 is chosen to be ink receptive. Imaging by electroerosion printing is carried out to selectively expose the intermediate layer. The conductive layer 8 must be ink repellent.
[0046] The following specific Examples are presented to illustrate the invention. All percentage and ratios are by weight unless otherwise set forth.
Example 1
[0047] A mixture of 30 parts of 20% cellulose acetate butyrate (CAB) solution in 4:1 tetrahydrofuran- toluene, 5.5 parts of amorphous silica (IMSIL-A-108H, available from Illinois Mineral Co., Illinois), 1 part of FluorographiteTM (Ozark-Mahoning, with degree of fluorination of 0.45-0.5), 0.3 parts of a polyester-polyol dispersing agent (R221-75, Mobay Chemical Co.) and 0.05 parts of a fluorocarbon surfactant (FC-430, 3M Co.), was ball milled for 24 hours to form a homogeneous dispersion (MILL BASE).
Coating formulation
[0048] The FluorographiteTM-containing MILL BASE, 10 parts, was mixed with 10 parts of a 20% CAB solution in 4:1 THF-toluene, 4.5 parts of polyisocyanate crosslinking agent (CB-75, Mobay Chemical Co.), 8 parts of a 4:1 THF-toluene mixture, 0.01 part of stannous octoate as the catalyst for the urethane forming reaction (T-9,from M & T Co.), and 0.01 parts of FC-430 surfactant. The mixture was agitated for 10 minutes and applied in a continuous casting process, by a conventional web coating technique, on the surface of a transparent MylarTM polyester (polyethylene terephthalate) film 51 pm (2 mil) thick, (XM-728, E.I. du Pont), followed by thermal treatment at 100°C for 5-10 minutes to accelerate solvent evaporation and the polymer curing process to provide a coating layer of 5-6 micron dry thickness. Thereafter, a thin film of aluminum, about 25-40 nm (250-400 Angstroms) thick, as the electrically conductive layer was deposited over the base layer by vacuum evaporation at 10-4―10-5 Pa (10-6―10-7 mmHg). The aluminum layer had electrical resistivity of 2-2.5 ohms per square centimeter. When this completed material was used for recording on a high speed electroerosion printer with a multistyli print head, excellent quality printing was observed with essentially no accumulation of the eroded debris on the print head even after hundreds of thousands of sweeps.
[0049] Head wear test results showed that the recording material of this invention causes a marked improvement in the wear life of the print head relative to a recording material prepared withoutthe incorporation of graphite fluoride and/ or fluorocarbon resins such as "Teflon" micropowders in the base layer.
[0050] The printed material prepared according to this example was employed as a high quality direct negative and as an offset master using the standard water dampening-ink cycle on the printing press to generate more than 3,000 prints of excellent quality.
Example 2
[0051] A mixture of 20 parts of a 20% CAB solution in 4:1 THF-toluene, 1.5 parts amorphous silica (IMSILA-108H), 0.15 parts of Fluorographite™ (x=0.45), 0.1 parts of a dispersing agent (R221-75) and 0.02 parts of FC-430 surfactant, was ball milled for 16 hours to form a homogeneous dispersion. This was mixed with a solution of 4.1 parts of polyisocyanate cross-linking agent (CB-75, Mobay) in 8 parts of a 4:1 mixture of THF and toluene, along with 0.01 parts of T-9 as the catalyst. The mixture was stirred for 10 minutes and applied as described in Example 1 to form a 4-5 pm thick lubricant base layer. The electrically conductive film, aluminum at 25―40 nm (250--400A) thickness was electrical resistance of 2.5 ohms/square centimeter was deposited by vacuum evaporation at 10-4―10-6 Pa (10-6―10-8 mmHg). The recording material thus prepared was tested on a high speed electroerosion printer. Again, excellent print quality, high resolution with essentially no accumulation of eroded debris on the print head, and a marked improvement in the wear characteristics of the print head were realized.
Example 3
[0052] A mixture of 10 parts of a 20% CAB solution in 4:1 THF-toluene, 1.0 part of amorphous silica, 0.1 part of TeflonR resin as a micropowder from du Pont, 0.05 part of a dispersing agent (R221-75) and 0.01 part of FC-430 surfactant, was ball milled for 16 hours to form a homogeneous dispersion. Prior to coating application, the dispersion was thoroughly mixed with a solution of 1.5 parts of polyisocyanate cross-linking agent (Desmodur N-75 from Mobay Chemical Co.) in 3.5 parts of a 4:1 mixture of THF-toluene. The mixture was applied as described in Examples 1 and 2 to form 4-6 micron thick lubricant base layer. Thereafter, a thin film of aluminum, about 25-40 nm (250-400A) thick, was deposited over the base layer by vacuum evaporation. The aluminized recording medium thus preapred upon printing on a high speed electroerosion printer provided an excellent quality direct negative which was also employed as an offset master for making more than 5,000 copies of high quality on a printing press using the standard water dampening-ink cycle.
1. An electroerosion recording material comprising a non-conductive support, a thin
layer of conductive material being evaporable in response to arcing and high local
temperatures obtained in the electroerosion recording process, and an intermediate
layer of thin, hard, polymer between said support and said layer of conductive material,
said intermediate layer containing graphite fluoride and/or a fluorocarbon polymer
as solid lubricant and a hard particulate material, the toughness of said intermediate
layer being sufficient to reduce plastics deformation of said support in response
to - stylus writing pressure, and the surface roughness of said intermediate layer
being sufficient to minimize scratching of said layer of conductive material during
the electroerosion recording process, while still serving to scour off from the electroerosion
stylus debris formed during electroerosion recording.
2. A recording material as claimed in Claim 1 wherein said recording material does
not include a lubricant overcoat.
3. A recording material as claimed in Claim 1 wherein said intermediate layer contains
a co-lubricant solid.
4. A recording material as claimed in Claim 3 wherein said co-lubricant solid is graphite.
5. A recording material as claimed in any one of claims 1 to 4, wherein said intermediate
layer comprises a cross-linked polymer matrix.
6. A material as claimed in anytwo of claims 1 to 5 wherein said conductive material
is a thin film of aluminum.
7. A material as claimed in any one of Claims 1 to 6 wherein graphite fluoride is
used as the solid lubricant.
8. A material as claimed in any one of Claims 1 to 6 wherein a fluorocarbon polymer
is used as the solid lubricant.
9. A material as claimed in any one of Claims 1 to 6 wherein graphite fluoride and
a fluorocarbon polymer are used in combination as the solid lubricant.
10. A material as claimed in any one of Claims 1 to 9 wherein said hard particulate
material is silica.
11. A material as claimed in any one of Claims 1 to 10, wherein said support and said
intermediate layer are light transmissive such that, after electroerosion of the conductive
member, the material may be utilized in direct-negative applications.
12. A material as claimed in any one of Claims 1 to 11, wherein the surface of said
conductive material is hydrophilic and said material is used in direct offset master
applications.
13. A method for producing an offset master by electroerosion processes comprising:
providing a sheet of electroerosion recording material comprising a nonconductive
support layer, a layer of conductive material capable of being eroded/ evaporated
during electroerosion recording, and a thin, ink receptive layer formed of a thin,
hard, hydrophobic polymer layer containing at least one of graphite fluoride and fluorocarbon
polymers as solid lubricants and a hard particulate material between said support
and said layer of conductive material, and subjecting said material to electroerosion
recording to remove said conductive layer and to expose said intermediate hydrophobic,
ink receptive layer in desired imaged areas, whereby said electroerosion recording
material may be used as an offset master after electroerosion recording.
14. A method for preparing a direct negative for use in photographic reproduction
comprising: providing a sheet of electroerosion recording material comprising a light
transmissive support layer, a layer of conductive material capable of being evaporated
during electroerosion recording, and an intermediate light-transmissive layer formed
of a thin, hard, hydrophobic polymer between said support and said layer of conductive
material and containing at least one of graphite fluoride and fluorocarbon polymers
as solid lubricants and a hard particulate material and subjecting said material to
electroerosion recording to remove at least said conductive layer in selected imaged
areas, creating light-transmissive paths through said imaged areas.
1. Ein Elektro-rosions-Aufnahmematerial mit einem nichtleitenden Träger, einer dünnen
Schicht leitfähigen Materials, das als Folge eines Lichbogens und hoher lokaler Temperaturen,
die in einem Elektroerosions-Aufnahmeprozess anfallen, verdampfbar ist und einer Zwischenschicht
aus dünnem, hartem Polymer zwischem dem Träger und der Schicht aus leitfähigem Material,
wobei die Zwischenschicht Graphitfluorid und/oder Fluorkohlenstoffpolymer als festen
Schmierstoffenthält und ein hartes aus Einzelteilen bestehendes Material, wobei die
Festigkeit der Zwischenschicht ausreichend ist, um die plastische Verformung des Trägers
als Folge einer Druckausübung einer Schreibstiftspitze zu verringern, und wobei die
Oberflächenauhigkeit der Zwischenschicht ausreichend ist, um ein Verkratzen der Schicht
aus leitfähigem Material während des Elektroerosions-Aufnahmevorgangs zu minimieren,
während dennoch ein Entschlammen von dem Elektroerosions-Schreiberabfall, der während
der Elektroerosions-Aufnahme entsteht, erreicht wird.
2. Aufnahmematerial nach Anspruch 1, worin das Aufnahmematerial keinen Schmierstoffüberzug
beinhaltet.
3. Aufnahmematerial nach Anspruch 1, worin die Zwischenschicht einen Festkörperschmierstoff
enthält.
4. Aufnahmematerial nach Anspruch 3, worin der Festkörperschmierstoff Graphit ist.
-
5. Aufnahmematerial nach einem der Ansprüche 1 bis 4, worin die Zwischenschicht eine
vernetzte Polymermatrix enthält.
6. Material nach einem der Ansprüche 1 bis 5, worin das leitfähige Material ein dünner
Aluminiumfilm ist.
7. Material nach einem der Ansprüche 1 bis 6, worin als Festkörperschmierstoff Graphitfluorid
verwendet wird.
8. Material nach einem der Ansprüche 1 bis 6, worin als Festkörperschmierstoff ein
FFuorkohlenstoffpolymer verwendet ist.
9. Material nach einem der Ansprüche 1 bis 6, worin in Kombination Graphitfluorid
und ein Fluorkohlenstoffpolymer als Festkörperschmierstoff verwendet ist.
10. Material nach einem der Ansprüche 1 bis 9, worin das harte, aus Einzeiteilen bestehende
Material Siliziumdioxid ist.
11. Material nach einem der Ansprüche 1 bis 10, worin der Träger und die Zwischenschicht
lichtdurchlässig sind, so daß nach der Elektroerosion des leitfähigen Bestandteils
das Material in direktnegativ Anwedungfällen verwendet werden kann.
12. Material nach einem der Ansprüche 1 bis 11, worin die Oberfläche des leitfähigen
Materials hydrophil ist und das Material in direkten Offset-Zwischenoriginal-Anwendungen
verwendet wird.
13. Verfahren zur Herstellung eine- Offset-Zwischenoriginals durch einen Elektroerosionsprozess,
das umfaßt: Bereitstellung eines Blattes aus Elektroerosions-Aufnahmematerial, das
eine nichtleitende Trägerschicht, eine Schicht leitfähigen Materials, geeignet, umd
während der Elektroerosions-Aufnahme abgetragen/verdampft zu werden, und eine dünne,
zur Aufnahme von Tinte fähige Lage, die aus einer dünnen, harten, hydrophilen Polymerschicht
gebildet ist, die als Festkörperschmierstoff zumindest eins von Graphitfluorid oder
Fluorkohlenstoffpolymer enthält und ein hartes aus Einzeitteilen bestehendes Material
zwischen dem Träger und der Schicht aus leitfähigem Material umfaßt und wobei das
Material der Elektroerosions-Aufnahme ausgesetzt wird, um die leitfähige Schicht zu
entfernen und die hydrophobe, zur Aufnahme von Tinte fähige Zwischenlage in gewünschten
abgebildeten Bereichen zu belichten, wodurch das Elektroerosions-Aufnahmematerial
nach der Elektroerosion-Aufnahme als ein Offset-Zwischenoriginal verwendbar ist.
14. Verfahren zur Herstellung eines direkten Negativs für die Anwendung bei der photographischen
Vervielfältigung, das umfaßt: Bereitstellung eines Blattes aus einem Elektroerosion-Aufnahmematerial,
das eine lichtdurchlässige Trägerschicht, eine Schicht aus leitendem Material, geeignet,
um während der Elektroerosion-Aufnahme verdampft zu werden, und eine lichtdurchlässige,
aus einem dünnen, harten, hydrophoben Polymer gebildete Zwischenlage zwischen dem
Träger und der Schicht leitfähigen Materials und die als Festkörperschmierstoffzumindesteinsvon
Graphitfluorid und Fluorkohlenstoffpolymer enthält und ein hartes aus Einzelteilen
bestehendes Material umfaßt und wobei das Material der Elektroerosion-Aufnahme ausgesetzt
wird, um zumindest die leitfähige Schicht in ausgewählten abgebildeten Bereichen zu
entfernen, wobei lichtdurchlässige Pfade durch die abgebildeten Bereiche geschaffen
werden.
1. Matériau d'enregistrement par électroérosion (6) comprenant un support non conducteur
(7), un couche mince de matériau conducteur (8) qui peut être évaporée sous l'effet
d'un arc et de températures localement élevées obtenues pendant un processus d'enregistrement
par électroérosion, et une couche intermédiaire (10) en un polymère mince et dur entre
ledit support et ladite couche de matériau conducteur, ladite couche intermédiaire
contenant du fluorure de graphite et/ou un polymère de fluorocarbone comme lubrifiant
solide et un matériau particulaire dur, la dureté de ladite couche intermédiaire étant
suffisante pour diminuer les déformations plastiques dudit support en réponse à la
pression d'une pointe d'écriture, et la rugosité de surface de ladite couche intermédiaire
étant suffisante pour minimiser le rayage de ladite couche de matériau conducteur
pendant la processus d'enregistrement par électroérosion tout en servant encore à
dégager de la pointe d'électroérosion les débris qui se forment pendant l'enregistrement
par électroérosion.
2. Matériau d'enregistrement selon la revendication 1, dans lequel le matéraiu d'enregistrement
ne comporte pas de pellicule de surface lubrifiante.
3. Matériau d'enregistrement selon la revendication 1, dans lequel- ladite couche
intermédiaire contient un solide colubrifiant.
4. Matériau d'enregistrement selon la revendication 3, dans lequel ledit solide co-lubrifiant
est de graphite.
5. Matériau d'enregistrement selon l'une quelconque des revendications 1 à 4, dans
lequel ladite couche intermédiaire comprend une matrice polymère réticulée.
6. Matériau selon deux quelconques des reven- teur est une couche mince d'aluminium.
7. Matériau selon l'une quelconque des revendications 1 à 6, dans lequel du fluorure
de graphite est utilisé comme lubrifiant solide.
8. Matériau selon l'une quelconque des revendications 1 à 6, dans lequel un polymère
de fluorocarbone est utilisé comme lubrifiant solide.
9. Matériau selon l'une quelconque des revendications 1 à 6, dans lequel du fluorure
de graphite et un polymère de fluorocarbone sont utilisés en combinaison comme lubrifiant
solide.
10. Matériau selon l'une quelconque des revendications 1 à 9, dans lequel ledit matériau
particulaire dur est de la silice.
11. Matériau selon l'une quelconque des revendications 1 à 10, dans lequel ledit support
et ladite couche intermédiaire sont transparents à la lumière de façon que, après
l'électroérosion de l'élément conducteur, le matériau puisse être utilisé dans des
applications de négatifs directs.
12. Matériau selon l'une quelconque des revendications 1 à 11, dans lequel la surface
dudit matériau conducteur est hydrophile et dans lequel ledit matériau est utilisé
pour des applications d'original d'offset direct.
13. Procédé pour produire un original d'offset par un processus d'électroérosion comprenant
les étapes suivantes: fournir une feuille de matériau d'enregistrement par électroérosion
comprenant une couche support non-conductrice, une couche de matériau conducteur qui
puisse être érodée/ évaporée lors de l'enregistrement par électroérosion, et une couche
mince réceptrice d'encre comprenant une couche de polymère mince, dure, et hydrophobe
comprenant au moins soit du fluorure de graphite soit des polymères de fluorocarbone
en tant que lubrifiants solides et un matériau particulaire dur entre ledit support
et ladite couche de matériau conducteur, et soumettre ledit matériau à l'enregistrement
par électroérosion pour enlever ladite couche conductrice et pour exposer ladite couche
intermédiaire hydrophobe et réceptrice d'encre selon des zones d'image voulues, d'où
il résulte que ledit matériau d'enregistrement par électroérosion peut être utilisé
comme un original d'offset après l'enregistrement par électroérosion.
14. Procédé de préparation d'un négatif direct pour l'utilisation en reproduction
photographique comprenant les étapes suivantes: fournir une feuille de matériau d'enregistrement
par électroérosion comprenant une couche support transparente à la lumière, une couche
de matériau conducteur qui puisse être évaporée pendant l'enregistrement par électroérosion,
et une couche intermédiaire transparente à la lumière constituée d'un polymère mince,
dur et hydrophobe entre ledit support et ladite couche de matériau conducteur et contenant
en moins soit du fluorure de graphite, soit des polymères de fluoroethane en tant
que lubrifiants solides et un matériau particulaire dur, et soumettre ledit matériau
à l'enregistrement par électroérosion pour supprimer au moins ladite couche conductrice
dans des zones d'image voulues, instaurant des chemins transparents à la